Synthesizing high-quality C-S-H seeds using the impinging stream precipitation method

The synthesized C-S-H seeds (CSs) are an important concrete admixture that can effectively accelerate cement hydration, thereby significantly enhancing the early strength of concrete. This study introduces a synthesis method for high-quality CSs utilizing an impinging stream reactor (ISR). Successful preparation in the ISR yielded high-quality CSs characterized by an agglomerate size of approximately 120 nm and a specific surface area of 35 m2/g. The micro-mixing efficiency strongly influences the size and acceleration performance of the CSs, emphasizing the pivotal role of efficient micro-mixing in producing superior-quality products. Moreover, the particle size of CSs can be effectively controlled by adjusting the reaction temperature, reactant concentration, and Ca/Si ratio. Calorimetric and mortar strength tests demonstrate that CSs synthesized in the ISR exhibit a significant acceleration of cement hydration. Notably, their accelerating performance surpasses that of CSs prepared in a stirred tank reactor (STR).